Critical island size for Ag thin film growth on ZnO (0 0 0<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:mrow></mml:math>)

Lloyd, Adam L.; Smith, Roger; Kenny, Steven D.

doi:10.1016/j.nimb.2016.10.026

Cited by 7 publications

(10 citation statements)

References 12 publications

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“…Figure c shows that Ag 4 , similarly to the Ag dopant, sits in the center of mass of the triangle formed by three oxygens. The adsorption site of Ag 4 is similar to the highly symmetric site described by Lloyd et al where they used lattice-based adaptive kinetic Monte Carlo (LatAKMC) to describe Ag adsorption on top of the polar ZnO(0001) surface. The average distance between Ag 4 and its neighboring oxygens is 2.442 Å, which is close to the average dopant–surface oxygen distance of 2.208 Å.…”

Section: Resultsmentioning

confidence: 99%

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Postica

Vahl

Santos‐Carballal

et al. 2019

ACS Appl. Mater. Interfaces

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Nanomaterials for highly selective and sensitive sensors toward specific gas molecules of volatile organic compounds (VOCs) are most important in developing new-generation of detector devices, for example, for biomarkers of diseases as well as for continuous air quality monitoring. Here, we present an innovative preparation approach for engineering sensors, which allow for full control of the dopant concentrations and the nanoparticles functionalization of columnar material surfaces. The main outcome of this powerful design concept lies in fine-tuning the reactivity of the sensor surfaces toward the VOCs of interest. First, nanocolumnar and well-distributed Ag-doped zinc oxide (ZnO:Ag) thin films are synthesized from chemical solution, and, at a second stage, noble nanoparticles of the required size are deposited using a gas aggregation source, ensuring that no percolating paths are formed between them. Typical samples that were investigated are Ag-doped and Ag nanoparticle-functionalized ZnO:Ag nanocolumnar films. The highest responses to VOCs, in particular to (CH3)2CHOH, were obtained at a low operating temperature (250 °C) for the samples synergistically enhanced with dopants and nanoparticles simultaneously. In addition, the response times, particularly the recovery times, are greatly reduced for the fully modified nanocolumnar thin films for a wide range of operating temperatures. The adsorption of propanol, acetone, methane, and hydrogen at various surface sites of the Ag-doped Ag8/ZnO(0001) surface has been examined with the density functional theory (DFT) calculations to understand the preference for organic compounds and to confirm experimental results. The response of the synergistically enhanced sensors to gas molecules containing certain functional groups is in excellent agreement with density functional theory calculations performed in this work too. This new fabrication strategy can underpin the next generation of advanced materials for gas sensing applications and prevent VOC levels that are hazardous to human health and can cause environmental damages.

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Section: Resultsmentioning

confidence: 99%

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Postica

Vahl

Santos‐Carballal

et al. 2019

ACS Appl. Mater. Interfaces

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“…Density functional theory (DFT) calculations were performed using the SIESTA package in order to provide quantum-chemical calculations with the same functionals and pseudopotentials as used in [5]. The systems chosen for the fitting process were the Al-Zn alloy in face centred cubic (FCC) and hexagonal closed packed (HCP) form, Al and double Al interstitials in ZnO, Al substitutional structures in ZnO and Al on a ZnO surface.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Methods of selecting the parameters have been studied in depth, see for example [12]. We can define how good each of the particles' fit is, based on the objective function that we defined in equation (5). A main benefit of the PSO is that it allows a global search of the parameters without knowing anything about the parameter space.…”

Section: Error Optimisationmentioning

confidence: 99%

“…In low-E coatings Ag is used as an infra-red blocker on a ZnO lattice. The ReaxFF formulation by Lloyd et al were able to construct a potential and carry out growth simulations of Ag on ZnO using an adaptive kinetic Monte-Carlo method [4,5] but so far the influence of Al on the ZnO growth process has not been considered. The aim of this work is to develop a potential that will accurately recreate low concentrations of Al interacting with the ZnO by using the existing ReaxFF model for ZnO [6] and performing ab initio calculations using SIESTA [7] for Al in ZnO to extend the parameterisation.…”

Section: Introductionmentioning

confidence: 99%

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A ReaxFF potential for Al–ZnO systems

Brown

Smith

Kenny

2022

Modelling Simul. Mater. Sci. Eng.

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A reactive field force (ReaxFF) potential has been created in order to model the structural effects of low percentage dopant aluminium in a zinc oxide system. The potential’s parameters were fitted to configurations computed with Density Functional Theory (DFT): cohesive energies, binding energies and forces were all considered for bulk crystals, surface structures and ZnAl alloys. As a first application of the model, the energetic deposition (0.1 - 40 eV) of an aluminium atom onto the polar surface of a ZnO (000 ̄1) is considered. For low energies the Al atom attaches to two preferred sites on the surface but as the energy increases above ≈ 15 eV subplantation is preferred at near normal incidence, with high diffusion barriers between stable sites. At these energies, reflection of the Al atom occurs at incident angles above ≈ 55◦.

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“…This method treats all possible adsorption sites for a lone Ag adatom on an existing Ag island as a single superbasin and transitions for the Ag adatom to drop down from on top of the island and join the cluster as the escaping mechanisms as reported in Ref. 32. The island sizes are extremely sensitive to temperature and the size of the barriers.…”

Section: E Lat-akmc Simulations On a Perfect Zno(0001) Surfacementioning

confidence: 99%

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

2018

Self Cite

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The growth of Ag on ZnO was modeled using a reactive force field potential and a combination of molecular dynamics and adaptive kinetic Monte Carlo (AKMC) simulations. An adaptive lattice-based AKMC model is described as a method of extending timescales and length scales that can be simulated. Reusing previously found transitions to reduce computational time is discussed for both the lattice and off-lattice AKMC approaches. With these methods, growth of over 1 monolayer's worth of Ag is simulated corresponding to a real deposition time of up to 0.1 s. The results show that the deposited silver aggregates on the surface through mainly single atom moves with few concerted motions. Initially silver adatoms do not agglomerate and the energy barriers for silver dimers to form are larger than for them to break apart. The first layer of silver grows as a series of connected regions rather than forming well-defined centro-symmetric islands.

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Critical island size for Ag thin film growth on ZnO (0 0 01¯)

Cited by 7 publications

References 12 publications

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

A ReaxFF potential for Al–ZnO systems

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

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